1. Field of the Invention
The present invention relates to a method of switching between multiple call signaling protocol stacks, and more particularly, to a method of real time switching in a packet-based network, and an apparatus using same.
2. Description of the Related Art
A Voice Quality Tester (VQT) is a device that measures various parameters of a phone call to quantify the impairments created by the telephone network. The measurement set is specifically designed to analyze packet based telephony networks or telephony networks that include packet based networks. These measurements include clarity, delay, echo, and signal loss.
The measurement process begins by establishing a call between two VQTs (or possibly the same VQT if multiple ports are supported on the interface in use). Different signaling methods are used to establish the call, dependent on the interface in use. Once the call is established and the media path is active, a measurement can be selected and configured to analyze the call path. For most measurements, a WAV file, or files representing speech, noise, or tone are transmitted over the network, and then received and processed by the VQT with the results subsequently displayed.
FIG. 1 is a block diagram of a conventional system 100 to test voice quality over a packet based network 160, for example, a Voice Over Internet Protocol (VOIP) network. The system 100 includes a first VQT 110 to test the packet based network 160 in connection with a second VQT 170. The system 100 further includes a call signaling protocol stack 120 (hereinafter “call signaling stack”) to provide a call signaling path to establish the call, and a media processing stack 130 to provide a call path for the call itself. A TCP/IP 140 connects the call signaling data and the call with a Local Area Network (LAN) interface 150, which interfaces with the packet based network 160.
The call signaling stack 120 operates according to a protocol, such as SIP or H.323. In order to support a different protocol, the call signaling stack 120 must be reconfigured with a different software download, or a different application must be used. This is disadvantageous because a complex series of steps is required, which increases the possibility of unexpected complications. Furthermore, the reconfiguration is costly, and consumes much time. Furthermore, there is limited ability to use the system 100 to measure different networks of different clients, and thus the network 100 must be customized for each particular client.
A second known system (not shown) exists, which tests call signaling interoperability and includes multiple call signaling stacks. However, this second known system tests whether or not a call can be established, but does not test the quality of the call path, and therefore is not a VQT.